Incoming calls webhook events not received inside business hours

Hello,
we have a free account application named "LeadsBridge Application". We use it for our business and we created an incoming call subscription through API for our customer.
When we retrieve subscriptions from API we obtain correctly the subscription

Our customer has some business hours configured in their account with id 2109957020.
When we try to do some calls to their phone number out of their business hours, we receive correclty webhook notification.
When we try to do some call inside their business hours we don't receive any webhook notification.

Do you have any idea what is causing this behaviour? Could be due to some account settings?
Of course we would like to receive webhook events always.